HCIL-92-09

Karl, L., Pettey, M., Shneiderman, B.
July 1992
International Journal of Man-Machine Studies, vol. 39, 4 (Oct. 1993) 667-687.
HCIL-92-09, CS-TR-2925, CAR-TR-630, SRC-TR-92-86.
Despite advances in speech technology, human factors research since the late 1970's has provided only weak evidence that automatic speech recognition devices are superior to conventional input devices such as keyboards and mice. However, recent studies indicate that there may be advantages to providing an additional input channel based on speech input to supplement the more common input modes. Recently the authors conducted an experiment to demonstrate the advantages of using speech-activated commands over mouse-activated commands for word processing applications when, in both cases, the keyboard is used for text entry and the mouse for direct manipulation. Sixteen experimental subjects, all professional and all but one novice users of speech input, p erformed four simple word processing tasks using both input groups in this counterbalanced experiment. Performance times for all tasks were significantly faster when using speech to activate commands as opposed to using the mouse. On average, the reduct ion in task time due to using speech was 18.67%. The error rates due to subject mistakes were roughly the same for bothinput groups, and recognition errors, averaged over all the tasks, occurred for 6.25% of the speech-activated commands. Subjects made significantly more memorization errors when using speech as compared with the mouse for command activation. Overall, the subjects reacted positively to using speech input and preferred it over the mouse for command activation, however, they also voiced c oncerns about recognition accuracy, the interference of background noise, inadequate feedback and slow response time. The authors believe that the results of the experiment provide guidance for implementors and evidence for the utility of speech input fo r command activation in application programs.
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